Process and apparatus for post deposition treatment of low dielectric materials

ABSTRACT

Methods and apparatus are provided for processing a substrate with an ultraviolet curing process. In one aspect, the invention provides a method for processing a substrate including depositing a silicon carbide dielectric layer on a substrate surface and curing the silicon carbide dielectric layer with ultra-violet curing radiation. The silicon carbide dielectric layer may comprise a nitrogen containing silicon carbide layer, an oxygen containing silicon carbide layer, or a phenyl containing silicon carbide layer. The silicon carbide dielectric layer may be used as a barrier layer, an etch stop, or as an anti-reflective coating in a damascene formation technique.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 11/123,265, filed May 5, 2005, which claims benefit of U.S.provisional patent application Ser. No. 60/569,373, filed May 6, 2004.Each of the aforementioned related patent applications is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the fabrication of integrated circuits, morespecifically to a process for forming dielectric layers on a substrate,and to the structures formed by the dielectric layer.

2. Description of the Related Art

Semiconductor device geometries have dramatically decreased in sizesince such devices were first introduced several decades ago. Sincethen, integrated circuits have generally followed the two year/half-sizerule (often called Moore's Law), which means that the number of devicesthat will fit on a chip doubles every two years. Today's fabricationplants are routinely producing devices having 0.35 μm and even 0.18 μmfeature sizes, and tomorrow's plants soon will be producing deviceshaving even smaller geometries.

To further reduce the size of devices on integrated circuits, it hasbecome necessary to use conductive materials having low resistivity andto use insulators having low dielectric constants (dielectric constantsof less than 4.0) to also reduce the capacitive coupling betweenadjacent metal lines. One such low k material is silicon oxycarbidedeposited by a chemical vapor deposition process and silicon carbide,both of which may be used as dielectric materials in fabricatingdamascene features.

One conductive material having a low resistivity is copper and itsalloys, which have become the materials of choice for sub-quarter-microninterconnect technology because copper has a lower resistivity thanaluminum, (1.7 μΩ-cm for copper compared to 3.1 μΩ-cm for aluminum), ahigher current and higher carrying capacity. These characteristics areimportant for supporting the higher current densities experienced athigh levels of integration and increased device speed. Further, copperhas a good thermal conductivity and is available in a highly pure state.

One difficulty in using copper in semiconductor devices is that copperis difficult to etch and achieve a precise pattern. Etching with copperusing traditional deposition/etch processes for forming interconnectshas been less than satisfactory. Therefore, new methods of manufacturinginterconnects having copper containing materials and low k dielectricmaterials are being developed.

One method for forming vertical and horizontal interconnects is by adamascene or dual damascene method. In the damascene method, one or moredielectric materials, such as the low k dielectric materials, aredeposited and pattern etched to form the vertical interconnects, forexample, vias, and horizontal interconnects, for example, lines.Conductive materials, such as copper containing materials, and othermaterials, such as barrier layer materials used to prevent diffusion ofcopper containing materials into the surrounding low k dielectric, arethen inlaid into the etched pattern. Any excess copper containingmaterials and excess barrier layer material external to the etchedpattern, such as on the field of the substrate, is then removed.

However, low k dielectric materials are often porous and susceptible tointerlayer diffusion of conductive materials, such as copper, which canresult in the formation of short-circuits and device failure. Adielectric barrier layer material is often disposed between the coppermaterial and surrounding the low k material to prevent interlayerdiffusion. However, traditional dielectric barrier layer materials, suchas silicon nitride, often have high dielectric constants of 7 orgreater. The combination of such a high k dielectric material withsurrounding low k dielectric materials results in dielectric stackshaving a higher than desired dielectric constant.

Further when silicon oxycarbide layers or silicon carbide layers thatcontain nitrogen are used as the low k material in damascene formation,it can be difficult to produced aligned features with little or nodefects. It has also been observed that resist materials deposited onthe silicon oxycarbide layers or the silicon carbide layers may becontaminated with nitrogen deposited with the silicon oxycarbide layersor the silicon carbide layers or from nitrogen diffusing therethrough.For example, reaction of organosilicon compounds with nitrous oxide cancontaminate the silicon oxycarbide layer with nitrogen or the nitrogenin nitrogen-doped silicon carbide layers may diffuse through adjacentlayers as amine radicals (—NH₂) to react with the resist materials.

Resist materials contaminated with nitrogen becomes less sensitive toradiation. Resist material exposed to other compounds, such as basicradicals including hydroxyl groups (—OH) may also decrease thesensitivity of the resist material. The decrease in the sensitivity toradiation is referred to as “resist poisoning”. Any resist material thatis not sensitive to radiation is not removed by subsequent resiststripping processes and remains as residue. The remaining residue ofresist material is referred to as “footing”. This residue can result indetrimentally affecting subsequent etching processes and result inmisaligned and malformed features.

Therefore, there remains a need for an improved process for depositingdielectric material and resist materials for layering techniques, suchas damascene applications.

SUMMARY OF THE INVENTION

Aspects of the invention generally provide a method for depositing andtreating a dielectric material having a low dielectric constant as abarrier layer, an etch stop, or an anti-reflective coating. In oneaspect, the invention provides a method for processing a substrateincluding depositing a silicon carbide dielectric layer on a substratesurface and curing the silicon carbide dielectric layer withultra-violet curing radiation.

In another aspect, the invention provides a method for processing asubstrate including depositing a first dielectric layer on the substrateby introducing a processing gas comprising a nitrogen containingcompound and an organosilicon compound into a processing chamber,reacting the processing gas to deposit a first dielectric layer, whereinthe first dielectric layer comprises silicon, carbon, and nitrogen, andhas a dielectric constant less than 5, and curing the first dielectriclayer with ultra-violet curing radiation.

In another aspect, a method is provided for processing a substrateincluding depositing a nitrogen-doped dielectric layer on the substrate,curing the nitrogen-doped dielectric layer with ultra-violet radiation,depositing a dielectric layer comprising silicon, oxygen, and carbon, onthe nitrogen-doped dielectric layer, depositing a resist on thedielectric layer comprising silicon, oxygen, and carbon.

In another aspect, an apparatus is provided for processing a substrateincluding a tandem-process chamber and a source of ultraviolet radiationdisposed on the tandem-processing chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings.

It is to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a cross sectional view showing a dual damascene structurecomprising a low k barrier layer and a low k dielectric layer describedherein;

FIGS. 2A-2H are cross sectional views showing one embodiment of a dualdamascene deposition sequence of the invention; and

FIG. 3 is a plan view of one embodiment of a tandem semiconductorprocessing system.

For a further understanding of aspect of the invention, reference shouldbe made to the ensuing detailed description.

DETAILED DESCRIPTION

The words and phrases used herein should be given their ordinary andcustomary meaning in the art by one skilled in the art unless otherwisefurther defined. The following deposition processes are described withuse of the 300 mm Producer™ dual deposition station processing chambercommercially available from Applied Materials Inc., of Santa Clara,Calif., of which one example is shown in FIG. 3, and should beinterpreted accordingly where appropriate. For example, flow rates forthe Producer™ processing chamber are total flow rates and should bedivided by two to describe the process flow rates at each depositionstation in the processing chamber. Additionally, it should be noted thatthe respective parameters may be modified to perform the plasmaprocesses in various chambers and for different substrate sizes, such asfor 200 mm substrates. Process parameters for the exposure to theultraviolet radiation may occur in the Producer™ processing chamber orseparate chamber or separate system.

Aspects of the invention described herein refer to a method andapparatus for depositing a silicon carbide containing layer having a lowdielectric constant, such as a nitrogen doped silicon carbide, andtreating the surface of the silicon carbide containing layer with anultraviolet curing process. Treating of the surface of the siliconcarbide containing material is believed to improve barrier properties,densify the silicon carbide containing material, limit the migration ofnitrogen contaminants from the deposited material or limit the abilityof nitrogen from reacting with the resist material, remove nitrogencontaining compounds from the deposited material, and reduce thedielectric constant of the silicon carbide containing material. Treatingthe surface may further include a plasma treatment or e-beam treatment.The surface treated with the ultraviolet curing process has beenobserved to be less reactive with the subsequently deposited resistmaterial thereby limiting resist poisoning and reduce defect formationwhen forming features in the dielectric layer. While the followingdescription is directed to depositing and treating a nitrogen dopeddielectric layer, the invention contemplates depositing and treatingnitrogen free dielectric layers, such as oxygen-doped silicon carbideand silicon carbide deposited from phenyl containing precursors asdescribed herein.

Silicon Carbide Deposition

Silicon carbide layer may be deposited by reacting a processing gas ofan organosilicon compound. Silicon carbide layer include a nitrogencontaining silicon carbide layer, an oxygen containing silicon carbidelayer, or a phenyl containing silicon carbide layer. The silicon carbidelayer may be deposited with an organosilicon compound and a reactivegas. For example, nitrogen-doped silicon carbide layers may be depositedby reacting a processing gas of the organosilicon compound and anitrogen containing compound. The processing gas may include additionalreactive compounds such as hydrogen gas. The processing gas may alsoinclude an inert gas including helium, argon, or combinations thereof.

Suitable organosilicon compounds for depositing silicon carbidematerials include oxygen-free organosilicon compounds. Examples ofoxygen free organosilicon compounds include phenylsilanes and aliphaticorganosilicon compounds. Examples of suitable organosilicon compoundsused herein for silicon carbide deposition preferably include thestructure:

wherein R includes hydrogen atoms or organic functional groups includingalkyl, alkenyl, cyclical, such as cyclohexyl, and aryl groups, inaddition to functional derivatives thereof. The organosilicon compoundsmay have more than one R group attached to the silicon atom, and theinvention contemplates the use of organosilicon compounds with orwithout Si—H bonds.

Suitable oxygen-free organosilicon compounds include oxygen-freealiphatic organosilicon compounds, oxygen-free cyclic organosiliconcompounds, or combinations thereof, having at least one silicon-carbonbond. Cyclic organosilicon compounds typically have a ring comprisingthree or more silicon atoms. Aliphatic organosilicon compounds havelinear or branched structures comprising one or more silicon atoms andone or more carbon atoms. Commercially available aliphatic organosiliconcompounds include alkylsilanes. Fluorinated derivatives of theorganosilicon compounds described herein may also be used to deposit thesilicon carbide and silicon oxycarbide layers described herein.Methylsilanes are preferred organosilicon compounds for silicon carbidedeposition.

Examples of suitable organosilicon compounds include, for example, oneor more of the following compounds: Methylsilane, CH₃—SiH₃Dimethylsilane, (CH₃)₂—SiH₂ Trimethylsilane (TMS), (CH₃)₃—SiHTetramethylsilane, (CH₃)₄—Si Ethylsilane, CH₃—CH₂—SiH₃ Disilanomethane,SiH₃—CH₂—SiH₃ Bis(methylsilano)methane, CH₃—SiH₂—CH₂—SiH₂—CH₃1,2-disilanoethane, SiH₃—CH₂—CH₂—SiH₃ 1,2-bis(methylsilano)ethane,CH₃—SiH₂—CH₂—CH₂—SiH₂—CH₃ 2,2-disilanopropane, SiH₃—C(CH₃)₂—SiH₃1,3,5-trisilano-2,4,6- —(—SiH₂—CH₂—)₃-(cyclic) trimethylene,Diethylsilane (C₂H₅)₂SiH₂ Diethylmethylsilane (C₂H₅)₂SiH(CH₃)Propylsilane C₃H₇SiH₃ Vinylmethylsilane (CH₂═CH)(CH₃)SiH₂Divinyldimethylsilane (CH₂═CH)₂(CH₃)₂Si (DVDMS)1,1,2,2-tetramethyldisilane HSi(CH₃)₂—Si(CH₃)₂H Hexamethyldisilane(CH₃)₃Si—Si(CH₃)₃ 1,1,2,2,3,3-hexamethyltrisilaneH(CH₃)₂Si—Si(CH₃)₂—SiH(CH₃)₂ 1,1,2,3,3-pentamethyltrisilaneH(CH₃)₂Si—SiH(CH₃)—SiH(CH₃)₂ DimethyldisilanoethaneCH₃—SiH₂—(CH₂)₂—SiH₂—CH₃ DimethyldisilanopropaneCH₃—SiH₂—(CH₂)₃—SiH₂—CH₃ Tetramethyldisilanoethane(CH)₂—SiH—(CH₂)₂—SiH—(CH)₂ Tetramethyldisilanopropane(CH₃)₂—SiH—(CH₂)₃—SiH—(CH₃)₂

Suitable organosilicon compounds further include alkyl and/or cyclicalorganosilicon compounds having carbon to silicon atom ratios (C:Si) of5:1 or greater, such as 8:1 or 9:1. Alkyl functional groups havinghigher carbon alkyl groups, such as ethyl and iso-propyl functionalgroups, for example, dimethylisopropylsilane (5:1), diethylmethylsilane(5:1), tetraethylsilane (8:1), dibutylsilanes (8:1), tripropylsilanes(9:1), may be used. Cyclical organosilicons, such as cyclopentylsilane(5:1) and cyclohexylsilane (6:1), including cyclical compounds havingalkyl groups, such as ethylcyclohexylsilane (8:1) andpropylcyclohexylsilanes (9:1) may also be used for the deposition ofsilicon carbon layers.

Phenyl containing organosilicon compounds, such as phenylsilanes mayalso be used for depositing the silicon carbide materials and generallyinclude the structure:

wherein R is a phenyl group. For example, suitable phenyl containingorganosilicon compounds generally include the formulaSiH_(a)(CH₃)_(b)(C₆H₅)_(c), wherein a is 0 to 3, b is 0 to 3, and c is 1to 4, and a+b+c is equal to 4. Examples of suitable compounds derivedfrom this formula include diphenylsilane (DPS), dimethylphenylsilane(DMPS), diphenylmethylsilane, phenylmethylsilane, and combinationsthereof. Preferably used are phenyl containing organosilicon compoundswith b is 1 to 3 and c is 1 to 3. The most preferred phenylorganosilicon compounds for deposition as barrier layer materialsinclude organosilicon compounds having the formulaSiH_(a)(CH₃)_(b)(C₆H₅)_(c), wherein a is 1 or 2, b is 1 or 2, and c is 1or 2. Examples of preferred phenyl compounds includedimethylphenylsilane and diphenylmethylsilane.

An example of a phenyl containing silicon carbide deposition processincludes supplying dimethylphenylsilane, to a plasma processing chamberat a flow rate between about 10 milligrams/minute (mgm) and about 1500mgm, for example, about 750 mgm, supplying hydrogen gas at a flow ratebetween about 10 sccm and about 2000 sccm, for example, about 500 sccm,supplying an inert gas at a flow rate between about 10 sccm and about10000 sccm, for example, about 1500 sccm, maintaining a substratetemperature between about 0° C. and about 500° C., for example, about350° C., maintaining a chamber pressure below about 500 Torr, forexample, about 6 Torr, and an RF power of between about 0.03 watts/cm²and about 1500 watts/cm², for example, about 200 watts at a gasdistributor positioned between about 300 mils and about 600 mils, forexample, about 450 mils, form the substrate surface during thedeposition process.

The RF power can be provided at a high frequency, such as between 13 MHzand 14 MHz. The RF power can be provided continuously or in shortduration cycles wherein the power is on at the stated levels for cyclesless than about 200 Hz and the on cycles total between about 10% andabout 30% of the total duty cycle. The processing gas may be introducedinto the chamber by a gas distributor, the gas distributor may bepositioned between about 200 mils and about 700 mils from the substratesurface. Additionally, the RF power may also be provided at lowfrequencies, such as 356 kHz, for depositing silicon carbide material.

Example processes for depositing a phenyl containing silicon carbidelayer is disclosed in U.S. Pat. No. 6,759,327, issued on Jul. 6, 2004,and U.S. Pat. No. 6,790,788, issued on Sep. 14, 2004, which areincorporated by reference to the extent not inconsistent with the claimsand disclosure described herein.

Nitrogen doped silicon carbide may be deposited by the reaction of theorganosilicon compounds described herein with a nitrogen containingcompound. The nitrogen containing compound may be a nitrogen-containinggas, for example, ammonia (NH₃), a mixture of nitrogen gas and hydrogengas, or combinations thereof, in the processing gas. The nitrogen dopedsilicon carbide layer generally includes less than about 20 atomicpercent (atomic %) of nitrogen. The nitrogen containing compound may beintroduced into the processing chamber at a flow rate between about 50sccm and about 10,000 sccm. The nitrogen doped silicon carbide layer mayfurther be oxygen doped by the processes described herein.

Alternatively, the nitrogen containing compound may comprise silicon andnitrogen containing compounds. Suitable silicon and nitrogen containingcompounds include compounds having Si—N—Si bonding groups, such assilazane compounds, may be used in the processing gas for doping thedeposited silicon carbide material with nitrogen. Compounds havingbonded nitrogen, such as in the silazane compounds, can improve thehardness of layers as well as reduced the current leakage of the layers.Examples of suitable silizane compounds includes aliphatic compounds,such as hexamethyldisilazane and divinyltetramethyldisilizane, as wellas cyclic compounds, such as hexamethylcyclotrisilazane.

One embodiment of a deposition of nitrated silicon carbide layercomprises supplying an organosilicon precursor, for exampletrimethylsilane, at a flow rate between about 10 sccm and about 1000sccm, such as between about 50 sccm and about 500 sccm, for example,about 350 sccm, supplying reducing compounds including nitrogencontaining compounds, to a processing chamber at a flow rate betweenabout 100 sccm and about 2500 sccm, such as, between about 500 sccm andabout 2000 sccm, for example, ammonia at 700 sccm, and optionally,supplying a hydrogen and/or an inert (noble) gas to a processing chamberat a flow rate between about 1 sccm and about 10,000 sccm respectively,for example, about 1200 sccm of helium, optionally supplying anoxygen-containing compound to a processing chamber at a flow ratebetween about 100 sccm and about 2500 sccm for an oxygen and nitrogendoped silicon carbide layer, for example, between about 500 sccm andabout 2000 sccm, maintaining a chamber pressure between about 100milliTorr and about 100 Torr, such as, between about 2.5 Torr and about9 Torr, for example, 3.7 Torr, maintaining a heater temperature betweenabout 100° C. and about 500° C., such as between about 250° C. and about450° C., for example, about 350° C., positioning a gas distributor, or“showerhead”, between about 200 mils and about 1000 mils, for example,280 mils from the substrate surface, and optionally, generating aplasma.

The plasma may be generated by applying a power density ranging betweenabout 0.03 W/cm2 and about 6.4 W/cm2, which is a RF power level ofbetween about 10 W and about 2000 W for a 200 mm substrate, for example,between about 500 W and about 1100 W, for example, 900 watts, at a highfrequency such as between 13 MHz and 14 MHz, for example, 13.56 MHz. Theplasma may be generated by applying a power density ranging betweenabout 0.01 W/cm² and about 2.8 W/cm², which is a RF power level ofbetween about 10 W and about 2000 W for a 300 mm substrate, for example,between about 500 W and about 1100 W at a high frequency such as between13 MHz and 14 MHz, for example, 13.56 MHz.

The power may be applied from a dual-frequency RF power source a firstRF power with a frequency in a range of about 10 MHz and about 30 MHz ata power in a range of about 200 watts to about 1000 watts and at least asecond RF power with a frequency in a range of between about 100 KHz andabout 500 KHz as well as a power in a range of about 1 watt to about 200watts. The initiation layer may be deposited for a period of timebetween about 1 second and 60 seconds, for example between about 1 andabout 5 seconds, such as 2 seconds.

Example processes for depositing a nitrogen containing silicon carbidelayer is disclosed in U.S. Pat. No. 6,764,958, issued on Jul. 20, 2004,and U.S. Pat. No. 6,537,733, issued on Mar. 25, 2003, which areincorporated by reference to the extent not inconsistent with the claimsand disclosure described herein.

The processing gas may further include hydrogen gas (H2) or an inertgas, or combinations thereof. Suitable inert gases include a noble gasselected from the group of argon, helium, neon, xenon, or krypton, andcombinations thereof. The hydrogen gas may be added at a molar ratio oforganosilicon compound to hydrogen gas of between about 1:1 and about10:1, such as between about 1:1 and about 6:1. Preferred depositionprocesses for oxygen-free organosilicon compounds and hydrogen gas has amolar ratio of oxygen-free organosilicon compound to hydrogen gas ofbetween about 1:1 and about 1.5:1. Generally, the flow rate hydrogen gas(H₂) and/or an inert gas is between about 50 sccm and about 20,000 sccm.

The silicon carbide layer may also be doped with boron and/or phosphorusto improve layer properties, and generally includes less than about 15atomic percent (atomic %) or less of dopants. Boron doping of the low ksilicon carbide layer may be performed by introducing borane (BH3), orborane derivatives thereof, such as diborane (B2H6), into the chamberduring the deposition process. Boron doping of the silicon carbide layerpreferably comprises between about 0.1 wt. % and about 4 wt. % of boron.

Phosphorus containing dopants may be used in the processing gases at aratio of dopant to organosilicon compound between about 1:5 or greater,such as between about 1:5 and about 1:100. Phosphorus doping of the lowk silicon carbide layer may be performed by introducing phosphine (PH3),triethylphosphate (TEPO), triethoxyphosphate (TEOP), trimethyl phosphine(TMP), triethyl phosphine (TEP), and combinations thereof, into thechamber during the deposition process. It is believed that dopants mayreduce the dielectric constant of the deposited silicon carbidematerial. The doped silicon carbide layer may comprise between about 0.1wt. % and about 15 wt. % of phosphorus, for example, between about 1 wt.% and about 4 wt. % of phosphorus.

Silicon carbide layers may further include oxygen. Oxygen-doped siliconcarbide layers typically include less than about 15 atomic percent(atomic %) of oxygen, preferably having between about 3 atomic % andabout 10 atomic % of oxygen. Oxygen doped silicon carbide layers may bedeposited with oxygen containing compounds including oxygen and carboncontaining compounds, such as oxygen containing gases and oxygencontaining organosilicon compounds. The oxygen-containing gas and theoxygen-containing organosilicon compound described herein are considerednon-oxidizing gases as compared to oxygen or ozone. Materials that aredescribed as silicon oxycarbide or carbon-doped silicon oxide generallycomprises between about 15 atomic % or greater of oxygen in the layerand are deposited from oxidizing gases.

Preferred oxygen-containing gases generally have the formula CXHYOZ,with x being between 0 and 2, Y being between 0 and 2, where X+Y is atleast 1, and Z being between 1 and 3, wherein X+Y+Z is 3 or less. Theoxygen-containing gas may include carbon dioxide, carbon monoxide, orcombinations thereof; and may additionally include water. Theoxygen-containing gas is typically an inorganic material.

Alternatively, oxygen-doped silicon carbide layers may be deposited withoxygen-containing organosilicon compounds to modify or change desiredlayer properties by controlling the oxygen content of the depositedsilicon carbide layer. Suitable oxygen-containing organosiliconcompounds include oxygen-containing aliphatic organosilicon compounds,oxygen-containing cyclic organosilicon compounds, or combinationsthereof. Oxygen-containing aliphatic organosilicon compounds have linearor branched structures comprising one or more silicon atoms and one ormore carbon atoms, and the structure includes silicon-oxygen bonds.

Oxygen-containing cyclic organosilicon compounds typically have a ringcomprising three or more silicon atoms and the ring may further compriseone or more oxygen atoms. Commercially available oxygen-containingcyclic organosilicon compounds include rings having alternating siliconand oxygen atoms with one or two alkyl groups bonded to each siliconatom. Preferred oxygen-containing organosilicon compounds are cycliccompounds.

One class of oxygen-containing organosilicon compounds include compoundshaving Si—O—Si bonding groups, such as organosiloxane compounds.Compounds with siloxane bonds provide silicon carbide layers with bondedoxygen that can reduce the dielectric constant of the layer as well asreduce the current leakage of the layer.

Suitable oxygen-containing organosilicon compounds include, for example,one or more of the following compounds: Dimethyldimethoxysilane(DMDMOS), (CH₃)₂—Si—(OCH₃)₂, Diethoxymethylsilane (DEMS),(CH₃)—SiH—(OCH₃)₂, 1,3-dimethyldisiloxane, CH₃—SiH₂—O—SiH₂—CH₃,1,1,3,3-tetramethyldisiloxane (TMDSO), (CH₃)₂—SiH—O—SiH—(CH₃)₂,Hexamethyldisiloxane (HMDS), (CH₃)₃—Si—O—Si—(CH₃)₃,Hexamethoxydisiloxane (HMDSO), (CH₃O)₃—Si—O—Si—(OCH₃)₃,1,3-bis(silanomethylene)disiloxane, (SiH₃—CH₂—SiH₂—)₂—O,Bis(1-methyldisiloxanyl)methane, (CH₃—SiH₂—O—SiH₂—)₂—CH_(2,)2,2-bis(1-methyldisiloxanyl)propane, (CH₃—SiH₂—O—SiH₂—)₂—C(CH₃)_(2,)1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS), —(—SiHCH₃—O—)₄-(cyclic),Octamethylcyclotetrasiloxane (OMCTS), —(—Si(CH₃)₂—O—)₄-(cyclic),1,3,5,7,9-pentamethylcyclopentasiloxane, —(—SiHCH₃—O—)₅-(cyclic),1,3,5,7-tetrasilano-2,6-dioxy-4,8-dimethylene, —(—SiH₂—CH₂—SiH₂—O—)₂—Hexamethylcyclotrisiloxane —(—Si(CH₃)₂—O—)₃-(cyclic)1,3-dimethyldisiloxane, CH₃—SiH₂—O—SiH₂—CH₃ Hexamethylcyclotrisiloxane(HMDOS) —(—Si(CH₃)₂—O—)₃-(cyclic),and fluorinated hydrocarbon derivatives thereof. The above lists areillustrative and should not be construed or interpreted as limiting thescope of the invention.

When oxygen-containing organosilicon compounds and oxygen-freeorganosilicon compounds are used in the same processing gas, a molarratio of oxygen-free organosilicon compounds to oxygen-containingorganosilicon compounds between about 4:1 and about 1:1 is generallyused. An example process for depositing an oxygen containing siliconcarbide layer is disclosed in U.S. patent application Ser. No.10/196,498, filed on Jul. 15, 2002, which is incorporated by referenceto the extent not inconsistent with the claims and disclosure describedherein.

An oxygen-doped silicon carbide layer may be deposited in one embodimentby supplying organosilicon compounds, such as trimethylsilane, to aplasma processing chamber at a flow rate between about 10milligrams/minute (mgm) and about 1500 mgm, for example about 160 mgm orsccm, supplying an oxidizing gas at a flow rate between about 10 sccmand about 2000 sccm, for example, about 700 sccm, supplying a noble gasat a flow rate between about 1 scorn and about 10000 sccm, for example,about 400 sccm, maintaining a substrate temperature between about 0° C.and about 500° C., for example, about 350° C., maintaining a chamberpressure below about 500 Torr, for example, about 2.5 Torr, at about andan RF power of between about 0.03 watts/cm² and about 1500 watts/cm²,for example about 200 Watts with a gas distributor may be positionedbetween about 200 mils and about 700 mils, for example about 320 mils,from the substrate surface.

The RF power can be provided at a high frequency such as between 13 MHzand 14 MHz or a mixed frequency of the high frequency and the lowfrequency. For example, a high frequency of about 13.56 MHz may be usedas well as a mixed frequency of high frequency of about 13.56 MHz andlow frequency of about 356 KHz. The RF power can be providedcontinuously or in short duration cycles wherein the power is on at thestated levels for cycles less than about 200 Hz and the on cycles totalbetween about 10% and about 30% of the total duty cycle. Additionally, alow frequency RF power may be applied during the deposition process. Forexample, an application of less than about 300 watts, such as less thanabout 100 watts at between about 100 KHz and about 1 MHz, such as 356KHz may be used to modify film properties, such as increase thecompressive stress of a SiC film to reduce copper stress migration.

Additional materials, such as an organic compounds, may also be presentduring the deposition process to modify or change desired layerproperties. For example, organic compounds, such as aliphatichydrocarbon compounds may also be used in the processing gas to increasethe carbon content of the deposited silicon carbide materials. Suitablealiphatic hydrocarbon compounds include compounds having between one andabout 20 adjacent carbon atoms. The hydrocarbon compounds can includeadjacent carbon atoms that are bonded by any combination of single,double, and triple bonds.

Suitable organic compounds may include alkenes and alkynes having two toabout 20 carbon atoms, such as ethylene, propylene, acetylene, andbutadiene. Further examples of suitable hydrocarbons includet-butylethylene, 1,1,3,3-tetramethylbutylbenzene, t-butylether,methyl-methacrylate (MMA), t-butylfurfurylether, and combinationsthereof. Organic compounds containing functional groups including oxygenand/or nitrogen containing functional groups may also be used. Forexample, alcohols, including ethanol, methanol, propanol, andiso-propanol, may be used for depositing the silicon carbide material.

Silicon carbide material are generally deposited by supplying anorganosilicon compound to a plasma processing chamber at a flow ratebetween about 10 sccm and about 1500 sccm, supplying a dopants, such asa nitrogen containing compounds including as ammonia and oxygencontaining compounds, at a flow rate between about 10 sccm and about2500 sccm, supplying additional gases, such as an inert gas and/orhydrogen, to the processing chamber at a flow rate between about 10 sccmand about 10000 sccm, respectively, maintaining the chamber at a heatertemperature between about 0° C. and about 500° C., maintaining a chamberpressure between about 100 milliTorr and about 100 Torr, positioning agas distributor between about 200 mils and about 700 mils from thesubstrate surface, and generating a plasma.

The plasma may be generated power levels may be by applying a powerdensity ranging between about 0.03 W/cm² and about 6.4 W/cm², which is aRF power level of between about 10 W and about 2000 W for a 200 mmsubstrate, for example, between about 100 W and about 400 W at a highfrequency such as between 13 MHz and 14 MHz, for example, 13.56 MHz. Theplasma may be generated power levels may be by applying a power densityranging between about 0.01 W/cm² and about 2.8 W/cm², which is a RFpower level of between about 10 W and about 2000 W for a 300 mmsubstrate, for example, between about 100 W and about 400 W at a highfrequency such as between 13 MHz and 14 MHz, for example, 13.56 MHz. TheRF power can be provided continuously or in short duration cycleswherein the power is on at the stated levels for cycles less than about200 Hz and the on cycles total between about 10% and about 30% of thetotal duty cycle. Alternatively, all plasma generation may be performedremotely, with the generated radicals introduced into the processingchamber for plasma treatment of a deposited material or deposition of amaterial layer.

Alternatively, the plasma may be generated by a dual-frequency RF powersource. The power may be applied from a dual-frequency RF power source afirst RF power with a frequency in a range of about 10 MHz and about 30MHz at a power, for example, in a range of about 100 watts to about 1000watts and at least a second RF power with a frequency in a range ofbetween about 100 KHz and about 500 KHz as well as a power, for example,in a range of about 1 watt to about 200 watts. The above processparameters provide a deposition rate for the silicon carbide layer inthe range of about 500 Å/min to about 20,000 Å/min, such as a rangebetween about 100 Å/min and about 3000 Å/min.

Suitable processing systems for performing the processes describedherein are a DxZ™ chemical vapor deposition chamber or Producer™processing system, both of which are commercially available from AppliedMaterials, Inc., Santa Clara, Calif.

The above process parameters provide a deposition rate for the siliconcarbide layer or nitrogen doped silicon carbide layer in the range ofabout 500 Å/min to about 20,000 Å/min, such as a range between about 100Å/min and about 3000 Å/min, when implemented on a 200 mm (millimeter)substrate in a deposition chamber available from Applied Materials,Inc., Santa Clara, Calif.

Ultraviolet Curing

The deposited silicon carbide material may then be cured by anultraviolet curing process. Silicon carbide material cured using theultraviolet curing process has shown an improved barrier layerproperties and reduced and minimal resist poisoning. The ultravioletcuring process may be performed in situ within the same processingchamber or system, for example, transferred from one chamber to anotherwithout break in a vacuum. The following ultraviolet curing process isillustrative, and should not be construed or interpreted as limiting thescope of the invention.

Exposure to an ultraviolet radiation source may be performed as follows.The substrate is introduced into a chamber, which may include thedeposition chamber, and a deposited silicon carbide layer, includingnitrogen-doped silicon carbide materials, is exposed to between about0.01 milliWatts/cm² and about 1 watts/cm² of ultraviolet radiation, forexample, between about 0.1 milliWatts/cm² and about 10 milliwatts/cm².The ultraviolet radiation may comprise a range of ultravioletwavelengths, and include one or more simultaneous wavelength. Suitableultraviolet wavelengths include between about 1 nm and about 400 nm, andmay further include optical wavelengths up to about 600 or 780 nm. Theultraviolet wavelengths between about 1 nm and about 400 nm, may providea photon energy (electroVolts) between about 11.48 (eV) and about 3.5(eV). Preferred ultraviolet wavelengths include between about 100 nm andabout 350 nm.

Further, the ultraviolet radiation application may occur at multiplewavelengths, a tunable wavelength emission and tunable power emission,or a modulation between a plurality of wavelengths as desired, and maybe emitted from a single UV lamp or applied from an array of ultravioletlamps. Examples of suitable UV lamps include a Xe filled Zeridex™ UVlamp, which emits ultraviolet radiation at a wavelength of about 172 nmor the Ushio Excimer UV lamp, or a Hg Arc Lamp, which emits ultravioletradioation at wave. The deposited silicon carbide layer is exposed tothe ultraviolet radiation for between about 10 seconds and about 600seconds.

During processing, the temperature of the processing chamber may bemaintained at between about 0° C. and about 450° C., for example,between about 20° C. and about 400° C. degrees Celsius, for exampleabout 25° C., and at a chamber pressure between vacuum, for example,less than about 1 mTorr up to about atmospheric pressure, i.e., 760Torr, for example at about 100 Torr. The source of ultraviolet radiationmay be between about 100 mils and about 600 mils from the substratesurface. Optionally, a processing gas may be introduced during theultraviolet curing process. Suitable processing gases include oxygen(O₂), nitrogen (N₂), hydrogen (H₂), helium (He), argon (Ar), water vapor(H₂O), carbon monoxide, carbon dioxide, hydrocarbon gases, fluorocarbongases, and fluorinated hydrocarbon gases, or combinations thereof. Thehydrocarbon compounds may have the formula C_(X)H_(Y), C_(X)F_(Y),C_(X)F_(Y)H_(Z), or combinations thereof, with x an integer between 1and 6, y is an integer between 4 and 14, and z is an integer between 1and 3.

An example of an ultraviolet process is as follows. A substrate having anitrogen doped silicon carbide layer is exposed to ultraviolet radiationat a chamber temperature about 400° C., an applied power of about 10mW/cm² at a wavelength of about 172 nm for about 120 seconds in an argonatmosphere at atmosphere pressure (about 760 Torr).

Alternative Post-Deposition Treatment:

The deposited silicon carbide material may also be exposed to an anneal,a plasma treatment or other post-deposition treatment process. Theanneal, plasma treatment, or other process may be performed before theultraviolet curing process, after the ultraviolet curing process, orboth before and after, with the before and after combination being thesame or different processes. The post-deposition treatments may beperformed in situ with the deposition of the silicon carbide materialwithout breaking vacuum in a processing chamber or processing system.

Annealing the deposited material may comprise exposing the substrate ata temperature between about 100° C. and about 400° C. for between about1 minute and about 60 minutes, preferably at about 30 minutes, to reducethe moisture content and increase the solidity and hardness of thedielectric material. Annealing is preferably performed after thedeposition of a subsequent material or layer that prevents shrinkage ordeformation of the dielectric layer. The annealing process is typicallyformed using inert gases, such as argon and helium, but may also includehydrogen or other non-oxidizing gases. The above described annealingprocess is preferably used for low dielectric constant materialsdeposited from processing gases without meta-stable compounds. Theanneal process is preferably performed prior to the subsequentdeposition of additional materials. Preferably, an in-situ (i.e., insidethe same chamber or same processing system without breaking vacuum) posttreatment is performed.

The annealing process is preferably performed in one or more cyclesusing helium. The annealing process may be performed more than once, andvariable amounts of helium and hydrogen may be used in multipleprocessing steps or annealing steps. The anneal energy may be providedby the use of heat lamps, infer-red radiation, such as IR heating lamps,or as part of a plasma anneal process. Alternatively, a RF power may beapplied to the annealing gas between about 200 W and about 1,000 W, suchas between about 200 W and about 800 W, at a frequency of about 13.56MHz for a 200 mm substrate.

Alternatively, or additionally, the deposited silicon carbide layer maybe plasma treated to remove contaminants or other wise clean the exposedsurface of the silicon carbide layer prior to subsequent deposition ofmaterials thereon. The plasma treatment may be performed in the samechamber used to deposit the silicon and carbon containing material. Theplasma treatment is also believed to improve film stability by forming aprotective layer of a higher density material than the untreated siliconcarbide material. The higher density silicon carbide material isbelieved to be more resistive to chemical reactions, such as formingoxides when exposed to oxygen, than the untreated silicon carbidematerial.

The plasma treatment generally includes providing an inert gas includinghelium, argon, neon, xenon, krypton, or combinations thereof, of whichhelium is preferred, and/or a reducing gas including hydrogen, ammonia,and combinations thereof, to a processing chamber. The inert gas orreducing gas is introduced into the processing chamber at a flow ratebetween about 500 sccm and about 3000 sccm, preferably between about1000 sccm and about 2500 sccm of hydrogen, and generating a plasma inthe processing chamber.

The plasma may be generated using a power density ranging between about0.03 W/cm² and about 3.2 W/cm², which is a RF power level of betweenabout 10 W and about 1000 W for a 200 mm substrate. Preferably, at apower level of about 100 watts for a silicon carbide material on a 200mm substrate. The RF power can be provided at a high frequency such asbetween 13 MHz and 14 MHz. The RF power can be provided continuously orin short duration cycles wherein the power is on at the stated levelsfor cycles less than about 200 Hz and the on cycles total between about10% and about 30% of the total duty cycle. Alternatively, the RF powermay also be provided at low frequencies, such as 356 kHz, for plasmatreating the depositing silicon carbide layer.

The processing chamber is preferably maintained at a chamber pressure ofbetween about 1 Torr and about 12 Torr, for example about 3 Torr. Thesubstrate is preferably maintained at a temperature between about 200°C. and about 450° C., preferably between about 290° C. and about 400°C., during the plasma treatment. A heater temperature of about the sametemperature of the silicon carbide deposition process, for example about290° C., may be used during the plasma treatment. The plasma treatmentmay be performed between about 10 seconds and about 100 seconds, with aplasma treatment between about 40 seconds and about 60 secondspreferably used. The processing gas may be introduced into the chamberby a gas distributor, the gas distributor may be positioned betweenabout 200 mils and about 500 mils from the substrate surface. The gasdistributor may be positioned between about 300 mils and about 600 milsduring the plasma treatment.

The hydrogen containing plasma treatment is believed to further reducethe dielectric constant of the low k dielectric layer by about 0.1. Theplasma treatment is believed to clean contaminants from the exposedsurface of the silicon carbide material and may be used to stabilize thelayer, such that it becomes less reactive with moisture and/or oxygenunder atmospheric condition as well as the adhesion of layers formedthereover.

One example of a post deposition plasma treatment for a silicon carbidelayer includes introducing ammonia at a flow rate of 950 sccm into theprocessing chamber, maintaining the chamber at a heater temperature ofabout 350° C., maintaining a chamber pressure of about 3.7 Torr,positioning a gas distributor at about 280 mils from the substratesurface, and applying a RF power of about 300 watts at 13.56 MHz forabout two seconds.

However, it should be noted that the respective parameters may bemodified to perform the plasma processes in various chambers and fordifferent substrate sizes, such as 300 mm substrates. An example of aplasma treatment for a silicon and carbon containing film is furtherdisclosed in U.S. patent application Ser. No. 09/336,525, entitled,“Plasma treatment to Enhance adhesion and to Minimize Oxidation ofCarbon-Containing Layers,” filed on Jun. 18, 1999, which is incorporatedherein by reference to the extent not inconsistent with the disclosureand claimed aspects of the invention described herein.

Alternatively, the silicon carbide layer may also be treated bydepositing a silicon carbide cap layer or silicon oxide cap layer priorto depositing a resist material. The cap layer may be deposited at athickness between about 100 Å and about 500 Å. The use of a cap layer ismore fully described in co-pending U.S. patent application Ser. No.09/977,008, entitled “Method Of Eliminating Resist Poisoning InDamascene Applications”, filed on Oct. 11, 2001, which is incorporatedherein by reference to the extent not inconsistent with the claimedaspects and disclosure described herein.

Electron Beam Treatment

In another aspect of the invention, the deposited silicon carbidematerial may be cured by an electronic beam (e-beam) technique inaddition to or as an alternative to ultraviolet radiation treatmentdescribed herein. Silicon carbide material cured using an e-beamtechnique has shown an unexpected reduction in k value and an unexpectedincrease in hardness, not capable with conventional curing techniques.The e-beam treatment may be performed in situ within the same processingsystem, for example, transferred from one chamber to another withoutbreak in a vacuum. The following e-beam apparatus and process areillustrative, and should not be construed or interpreted as limiting thescope of the invention.

The temperature at which the electron beam apparatus 200 operates rangesfrom about −200 degrees Celsius to about 600 degrees Celsius, forexample, about 400 degrees Celsius. An e-beam treatment of a siliconcarbide layer may comprise the application or exposure to between about1 micro coulombs per square centimeter (μC/cm²) and about 6,000 μC/cm²,for example, between about 1 μC/cm² and about 400 μC/cm², and morepreferably less than about 200 μC/cm², such as about 70 μC/cm², atenergy ranges between about 0.5 kiloelectron volts (KeV) and about 30KeV, for example between about 1 KeV and about 3 kiloelectron volts(KeV). The electron beams are generally generated at a pressure of about1 mTorr to about 200 mTorr.

The gas ambient in the electron beam chamber 220 may be an inert gas,including nitrogen, helium, argon, xenon, an oxidizing gas includingoxygen, a reducing gas including hydrogen, a blend of hydrogen andnitrogen, ammonia, or any combination of these gases. The electron beamcurrent ranges from about 1 mA to about 40 mA, and more preferably fromabout 5 mA to about 20 mA. The electron beam may cover an area fromabout 4 square inches to about 700 square inches. Although any e-beamdevice may be used, one exemplary device is the EBK chamber, availablefrom Applied Materials, Inc., of Santa Clara, Calif.

A general example of an e-beam process is as follows. A substrate havinga 3000 Å thick layer is exposed to an e-beam at a chamber temperatureabout 400 degrees Celsius, an applied electron beam energy of about 3.5KeV, and at an electron beam current of about 5 mA, with an exposuredose of the electron beam of about 500 mC/cm2.

Further description of an e-beam process for silicon carbon materials ismore fully described in co-pending U.S. Pat. No. 6,790,788, issued onSep. 14, 2004, which is incorporated herein by reference to the extentnot inconsistent with the claimed aspects and disclosure describedherein.

Deposition of a Barrier Layer for a Dual Damascene Structure

The ultraviolet cured silicon carbide layer, including nitrogen dopedsilicon carbide layers may be used as barrier layers, etch stop, andanti-reflective coating/passivation layers in damascene formation, ofwhich use as a barrier layer is preferred. Interlayer dielectric layersfor use in low k damascene formations having silicon carbide layerformed as described herein include dielectric layers having silicon,oxygen, and carbon, and a dielectric constant of less than about 3. Theadjacent dielectric layers for use with the barrier layer materialdescribed herein have a carbon content of about 1 atomic percent orgreater excluding hydrogen atoms, preferably between about 5 and about30 atomic percent excluding hydrogen atoms, and have oxygenconcentrations of about 15 atomic % or greater.

The adjacent dielectric layer may be deposited by oxidizing anorganosiliane compound in a plasma enhanced chemical vapor depositiontechnique. For example, a suitable adjacent dielectric material may bedeposited by reacting trimethylsilane and oxygen in a plasma enhancedchemical vapor deposition technique, with the plasma formed underconditions including a high frequency RF power density from about 0.16W/cm² to about 0.48 W/cm². Examples of methods and uses for the adjacentdielectric layers comprising silicon, oxygen, and carbon, having adielectric constant of less than about 3 are more further described inU.S. Pat. No. 6,054,379, issued May 25, 2000, U.S. Pat. No. 6,287,990,issued Sep. 11, 2001, and U.S. Pat. No. 6,303,523, issued on Oct. 16,2001, which are incorporated by reference herein to the extent notinconsistent with the disclosure and claimed aspects described herein.An example of a dielectric layer comprising silicon, oxygen, and carbon,having a dielectric constant of less than about 3 is Black Diamond™dielectric materials commercially available from Applied Materials,Inc., of Santa Clara, Calif.

The embodiments described herein for depositing silicon carbide layersadjacent low k dielectric layers are provided to illustrate theinvention and the particular embodiment shown should not be used tolimit the scope of the invention.

An example of a damascene structure that is formed using the siliconcarbide material described herein as a barrier layer is shown in FIG. 1.A silicon carbide barrier layer 110, such as nitrogen-doped siliconcarbide, is deposited and post deposition treated with ultravioletradiation as described herein on the substrate surface to eliminateinter-level diffusion between the substrate and subsequently depositedmaterials. The substrate surface may comprise metal features 107, suchas copper features, formed in a dielectric material 105. Optionally, asecond barrier layer of a oxygen containing silicon carbide layer or aphenyl containing silicon carbide layer as described herein may bedeposited on the silicon carbide barrier layer 110.

A first dielectric layer 112, comprising silicon, oxygen, and carbon, asdescribed herein, is deposited on the silicon carbide barrier layer 110.An etch stop (or second barrier layer) 114 of a silicon carbidematerial, such as the nitrogen and/or oxygen doped silicon carbidematerial described herein, is then deposited on the first dielectriclayer 112 and treated with ultraviolet radiation as described herein.The etch stop 114 is then pattern etched using conventional techniquesto define the openings 116 of the interconnects or contacts/vias.

A second dielectric layer 118 is then deposited over the patterned etchstop. A resist is then deposited and patterned by conventional meansknown in the art to define the contacts/vias openings 116. A resistmaterial may include an energy based resist material including deepultraviolet (DUV) resist materials as well as e-beam resist materials.

A single etch process is then performed to define the contacts/viasopenings 116 down to the etch stop and to etch the unprotecteddielectric exposed by the patterned etch stop to define thecontacts/vias openings 116. One or more conductive materials 120 such ascopper are then deposited to fill the formed contacts/vias openings 116.While not shown, an optional silicon carbide layer, may be deposited onthe second dielectric layer 118 and treated with ultraviolet radiationas described herein prior to deposition of the resist material. Theoptional silicon carbide layer may perform as a anti-reflective coating,a passivation layer, or both. The optional silicon carbide layer ispreferably a nitrogen free silicon carbide material, and the inventioncontemplates that a nitrogen doped silicon carbide layer with theultraviolet curing may also be used.

A preferred dual damascene structure fabricated in accordance with theinvention including a silicon carbide barrier layer deposited by theprocesses described herein is sequentially depicted schematically inFIGS. 2A-2H, which are cross sectional views of a substrate having thesteps of the invention formed thereon.

As shown in FIG. 2A, a nitrogen doped silicon carbide barrier layer 110is deposited on the substrate surface from the processes describedherein. The silicon carbide barrier layer 110 may be deposited byintroducing ammonia at a flow rate of 700 sccm into the processingchamber, introducing helium at a flow rate of 1200 sccm into theprocessing chamber, introducing trimethylsilane (TMS) at a flow rate ofabout 350 sccm, maintaining the chamber at a heater temperature of about350° C., maintaining a chamber pressure of about 3.7 Torr, positioning agas distributor at about 280 mils from the substrate surface, andapplying a RF power of about 900 watts at 13.56 MHz, to deposit asilicon carbide layer. The silicon carbide material is deposited atabout 1300 Å/min by this process. The deposited silicon carbide layerhas a dielectric constant of about 3.5.

The silicon carbide barrier layer 110 may then be treated to theultraviolet curing as described herein or another or additional postdeposition process, such as an anneal or e-beam or plasma treated asdescribed herein. The ultraviolet cure treatment may be performed insitu with the deposition of the silicon carbide material. Such anultraviolet cure treatment is believed to harden and stabilize thelayer, such that it becomes less reactive with moisture and/or oxygenunder atmospheric condition as well as the adhesion of layers formedthereover. An example of an ultraviolet curing includes exposing thesilicon carbide barrier layer 110 exposed to ultraviolet radiation at achamber temperature about 25° C., an applied power of about 10 mW/cm² ata wavelength of about 172 nm for about 120 seconds. Alternatively, theprocessing chamber is maintained at a pressure and at a heatertemperature of about the pressure and heater temperature during thesilicon carbide barrier deposition process during the ultravioletcuring.

Alternatively, or additionally, a capping layer (not shown) of anitrogen free silicon carbide material may be deposited on the siliconcarbide barrier layer 110. The nitrogen free silicon carbide cappinglayer may be deposited in situ on the silicon carbide barrier layer 110.The capping layer is preferably deposited after any e-beam or plasmatreatment of silicon carbide barrier layer 110.

The first dielectric layer 112 of interlayer dielectric material isdeposited on the first silicon carbide barrier layer 110 by oxidizing anorganosilane or organosiloxane, such as trimethylsilane. The firstdielectric layer 112 may be deposited to a thickness of about 5,000 Å toabout 15,000 Å, depending on the size of the structure to be fabricated.An example of a low dielectric constant material that may be used as aninterlayer dielectric material is Black Diamond™ dielectric commerciallyavailable from Applied Materials, Inc., of Santa Clara, Calif.Alternatively, the first dielectric layer may also comprise other low kdielectric material such as a low k polymer material including paralyneor a low k spin-on glass such as un-doped silicon glass (USG) orfluorine-doped silicon glass (FSG).

As shown in FIG. 2B, the low k etch stop 114, which may be a siliconcarbide material as described herein, is then deposited on the firstdielectric layer. The etch stop may be deposited to a thickness betweenabout 200 Å and about 1000 Å. The low k etch stop 114 may be depositedfrom the same precursors and by the same process as the silicon carbidebarrier layer 110. The low k etch stop 114 may be treated as describedherein for the silicon carbide barrier layer 110. A capping layer (notshown) may also be deposited on the low k etch stop 114 as described forthe silicon carbide barrier layer 100 described herein.

The low k etch stop 114 may then pattern etched to define thecontact/via openings 116 and to expose first dielectric layer 112 in theareas where the contacts/vias are to be formed as shown in FIG. 2C.Preferably, the low k etch stop 114 is pattern etched using conventionalphotolithography and etch processes using fluorine, carbon, and oxygenions. While not shown, a nitrogen-free silicon carbide or silicon oxidecap layer between about 100 Å and about 500 Å thick may be deposited onthe etch stop 114 prior to depositing further materials.

After the low k etch stop 114 has been etched to pattern thecontacts/vias and the resist has been removed, a second dielectric layer118 of silicon oxycarbide is deposited. The second dielectric layer maybe deposited to a thickness between about 5,000 and about 15,000 Å asshown in FIG. 2D. The second dielectric layer 118 may be deposited asdescribed for the first dielectric layer 112 as well as comprise thesame materials used for the first dielectric layer 112. The first andsecond dielectric layer 118 may also be treated as described herein forsilicon carbide barrier layer 110.

In an alternative embodiment, a nitrogen-free silicon carbide or siliconoxide cap layer may be deposited on second dielectric layer 118 prior todepositing additional materials, such as resist materials. Such a layermay be deposited between about 100 Å and about 500 Å thick. In a furtheralternative embodiment, a silicon carbide cap layer (not shown) may bedeposited from the same precursors are by the same process as thesilicon carbide barrier layer 110 on the second dielectric layer 118prior to depositing additional materials, such as resist materials.

A resist material 122 is then deposited on the second dielectric layer118 (or optional ARC layer or passivation layer as described with regardto FIG. 1) and patterned preferably using conventional photolithographyprocesses to define the copper material 120 interconnect lines as shownin FIG. 2E. The resist material 122 comprises a material conventionallyknown in the art, preferably a high activation energy resist, such asUV-5, commercially available from Shipley Company Inc., of Marlborough,Mass. The interconnects and contacts/vias are then etched using reactiveion etching or other anisotropic etching techniques to define themetallization structure (ie., the interconnect and contact/via) as shownin FIG. 2F. Any resist or other material used to pattern the etch stop114 or the second dielectric layer 118 is removed using an oxygen stripor other suitable process.

The metallization structure is then formed with a conductive materialsuch as aluminum, copper, tungsten or combinations thereof. Presently,the trend is to use copper to form the smaller features due to the lowresistivity of copper (1.7 mΩ-cm compared to 3.1 mΩ-cm for aluminum).Preferably, as shown in FIG. 2G, a suitable barrier layer 124 forcopper, such as tantalum or tantalum nitride, is first depositedconformally in the metallization pattern to prevent copper migrationinto the surrounding silicon and/or dielectric material. Thereafter,copper 126 is deposited using chemical vapor deposition, physical vapordeposition, electroplating, or combinations thereof to form theconductive structure. Once the structure has been filled with copper orother metal, the surface is planarized using chemical mechanicalpolishing, as shown in FIG. 2H.

Apparatus

FIG. 3 is a plan view of one embodiment of a semiconductortandem-chamber processing system 300 in which embodiments of theinvention may be used to advantage. The arrangement and combination ofchambers may be altered for purposes of performing specific fabricationprocess steps. Sources of the ultraviolet radiation may be disposed onvarious locations of the processing tool.

The tandem-chamber processing system 300 is a self-contained systemhaving the necessary processing utilities supported on a mainframestructure 301 which can be easily installed and which provides a quickstart up for operation. The tandem-chamber processing system 300generally includes four different regions, namely, a front end stagingarea 302 where substrate cassettes 309 are supported and substrates areloaded into and unloaded from a loadlock chamber 312, a transfer chamber311 housing a substrate handler 313, a series of tandem-processingchambers 306 mounted on the transfer chamber 311 and a back end 338which houses the support utilities needed for operation of thetandem-chamber processing system 300, such as a gas panel 303, and thepower distribution panel 305 for RF power generators 307. The tandemprocessing chambers include two processing regions 318 for processingsubstrates. The system can be adapted to accommodate various processesand supporting chamber hardware such as CVD, PVD, etch, and the like.

Sources of ultraviolet radiation 340, 342 may be disposed on thetandem-processing chambers 306 or the loadlock chamber 312 to integratewith a system processing regime. Alternatively, a source of ultravioletradiation may be used in the place of one of thetandem-tandem-processing chambers 306. Further, the source ofultraviolet radiation may be position ex situ of the tandem-chamberprocessing system 300. The source of ultraviolet radiation may be anultraviolet lamp, an ultraviolet laser, an ultraviolet electron beam, anultraviolet imaging system, such as a DUV resist imaging system, orother form of ultraviolet radiation emitter.

The above apparatus is one embodiment of a Producer™ processing system,commercially available from Applied Materials, Inc., of Santa Clara,Calif., suitable for chemical vapor deposition of materials, such as thesilicon carbide materials described herein. The plan-view in FIG. 3, isprovided for illustrative purposes, and FIG. 3 and the correspondingdescription should not be interpreted or construed as limiting the scopeof the invention. An example of the processing described herein isfurther detailed in commonly owned U.S. Pat. No. 6,591,850, issued onJul. 15, 2003, which is incorporated by reference to the extent notinconsistent with the disclosure and claimed aspects herein.

While the foregoing is directed to preferred embodiments of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. An apparatus for processing a substrate comprising: a tandem-process chamber; and a source of ultraviolet radiation disposed on the tandem-processing chamber.
 2. The apparatus of claim 1 wherein the source of ultraviolet radiation comprises an ultraviolet lamp, an ultraviolet laser, an ultraviolet electron beam, or an ultraviolet imaging system.
 3. The apparatus of claim 1 wherein the source of ultraviolet radiation provides ultraviolet radiation between about 0.1 milliWatts/cm² and about 1 watts/cm² at between about 100 nm and about 400 nm.
 4. The apparatus of claim 1 wherein the tandem-process chamber comprises two isolated processing regions.
 5. The apparatus of claim 1 wherein the tandem-process chamber is coupled to a transfer chamber, and the transfer chamber is coupled to a loadlock chamber and is coupled to a backend comprising a gas panel, a power distribution panel, and a RF power generator. 